Material Colors don't show when exporting?
Most exporters will only handle very basic Principled BSDF materials. You can make a Principled material that will look like you want by putting black in the &quot;Base Color&quot; socket and putting the color you want in the &quot;Emission&quot; socket. (You may also want to try cranking the roughness up to 1.)

I tried exporting this with .fbx/.obj/.glb and reimporting, and they all worked.